Silver halide light sensitive photographic materials (hereinafter, referred to as photographic materials), which have enhanced properties such as high sensitivity and excellent tone reproduction as compared to other print materials, are widely employed. An image forming method has been known, employing amplification development of a silver halide photographic material, in which advantageous effects of the silver halide photographic material are displayed, in which consumption of silver halide can be reduced, and which is preferable in terms of effective use of natural resources. As an example of the amplification development is cited a method in which an oxidized color developing agent is formed by using an oxidizing agent such as hydrogen peroxide or a cobalt (III) complex in the presence of developed silver as a catalyst and subsequently, a dye image is formed upon reaction with a coupler. Of these, the amplification development by the use of hydrogen peroxide as an oxidizing agent is preferred in terms of high amplification efficiency and reduced environmental load.
Amplification development is comprised of a silver developing process which forms catalytically active silver nuclei and an amplification process of amplification development catalyzed by the silver nuclei. WO 93/11460 and JP-A 7-159960 and 7-175190 (the term, JP-A refers to an unexamined and published Japanese Patent Application) disclose an image forming method by the use of an amplification developing solution concurrently containing a developing agent and an oxidizing agent (alternatively, denoted as a single solution type amplification development). Since the silver development and amplification processes simultaneously proceed in the single solution amplification development, there occur problems such that an optimum condition for each process can not be simultaneously achieved, making it difficult to obtain images with satisfied photographic performance, and the developing solution concurrently which contains an oxidizing agent and a reducing agent which deteriorates more quickly and is inferior in aging stability. Further, WO 92/07299 and 93/01524, JP-A 61-8, 61-80150, 61-88259, 6-313954, 7-77788, 9-106052 and 9-127664 disclose image forming methods, in which to separate the amplification process from the silver development process, plural processing solutions are employed, the silver development is performed in the first processing solution, and the amplification is performed in the second processing solution (hereinafter, denoted as dual solution type amplification development).
In the image forming method by employing conventional color development which is the prevalent trend of development in the market, the use of high chloride containing silver halide emulsion results in shortened processing time, however, further rapid access is still desired. Through improvements of equipments such as automatic processors and printers, photographic processing solutions and photographic materials, so-called mini-labs have widely spread. Such mini-labs can be installed in a small area and are easily operated. There is still desired, however, a mini-lab with a low price and capable of forming stable and high quality images.
In the dual solution type amplification development described in JP-A 61-80149, 61-80150, 61-88259, 6-313954 and 7-77788; WO 92/07299 and 93/01524, it is difficult to simultaneously achieve both shortening of the amplification developing time and sufficient density, and therefore further improvement in these area is still desired. Further, in the dual solution type amplification development described in JP-A 9-106052 and 9-127664, it was proved that when being continuously processed, the density in the midscale density portion tended to fluctuate and its improvement is still sought.